Rut Brandt was for 32 years married to Willy Brandt, supporting him during his early political career in post-war Germany through his time as Mayor of West Berlin, Foreign Minister and, from 1969 to 1974, Chancellor. On more than one occasion, when Brandt was on the point of giving up the leadership of the German Social Democratic Party, Rut was a decisive influence in his resolve to carry on. Stylish and good-looking, she was a popular and successful First Lady, a Jackie Kennedy of the Social Democrats.

Born Rut Hansen in Hamar, a small market town in Norway in 1920, her father, a chauffeur, died when she was only three. After leaving school aged 15, Rut started work in a bread shop. Later she became an apprentice tailor. As her mother was a socialist and a Christian it was not surprising that by 16 Rut was already politically active in a socialist youth group.

When the Germans occupied Norway, in 1940, Rut Hansen became active in the resistance. Exposed, in 1942, its members sought sanctuary in neutral Sweden. There Rut married a fellow Norwegian socialist, a railwayman called Ole Olstadt Bergaust. Both had found employment in the Norwegian embassy. It was in these resistance circles that she also got to know, in 1944, Willy Brandt, a German socialist émigré journalist. Brandt had found refuge from Nazi Germany in Norway and then fled to Sweden. The two soon became an item. Rut's husband died in 1946 and Brandt divorced his Norwegian wife, Carlotta Thorkildsen.

While reporting for Norwegian papers on the Nuremberg trials Brandt made contact with surviving comrades from the pre-Hitler days. In 1947, he returned to divided Berlin as a press attaché of the Norwegian military mission. Rut went with him as his secretary. They married in 1948 and three sons followed: Peter, Lars and Matthias.

Brandt gave up his Norwegian post and nationality and became a German citizen again and took a Berlin job with the struggling SPD. For Willy, Rut had given up the comfortable lifestyle of a Scandinavian with a diplomatic pass, for the life of a German under occupation, and in a city under blockade by the Soviets, where food and fuel were short and social democrats risked being kidnapped by the Russians.

Willy Brandt was elected to parliament in 1949 and served as mayor of West Berlin from 1957 to 1966, a post in which he achieved world fame. His party's hopes were high when he was their candidate for Chancellor, in 1965. His failure in that election, in which bitter personal attacks were made on him, led him to announce his resignation as leader. However, Rut played a considerable part in getting him to carry on. With her elegance on the one hand and her ability to speak to rank-and-file party members on the other, she helped to rally support.

In 1966, he became Deputy Chancellor and Foreign Minister in a grand coalition, which paved the way for his narrow election victory in 1969. Rut never sought office herself. Good-looking, perhaps she could have had a career as an actress. In the early post-war years she had small parts in several films including Anatole Litvak's true war story Decision Before Dawn (1951).

Brandt was the subject of rumours throughout his career. Only after his death was his relationship with the journalist Heli Ihlefeld made public. His fall from office, in 1974, due to the exposure of an assistant, Günter Guillaume, as an East German spy, led to more speculation that Guillaume procured women for Brandt. When, in 1979, Brandt formed a relationship with Brigitte Seebacher, an SPD journalist and historian 33 years his junior, Rut filed for divorce. After this was finalised, she never saw Willy again. On his death, in 1992, Seebacher refused to allow Rut Brandt to be present at the state ceremony of commemoration.

Rut Brandt published two books of memoirs, Freundesland ("Land of Friends") in 1992 and, in 2003, Wer an wen sein Herz verlor: Begegnungen und Erlebnisse ("Who lost his heart to whom: encounters and experiences").